This invention relates generally to prime movers and, more particularly, has reference to a new and improved prime mover module used in a fluid delivery micropump, especially for pharmaceutical applications.
In various clinical situations, the indicated procedure for treating the patient is to administer pharmaceutical fluids into his body at a sustained, very low rate over an extended period of time. Fluids administered in this manner include liquid nutrients, blood, plasma, insulin and hormones.
The traditional apparatus for the gradual administration of liquids into the human body is the intravenous administration set in which gravity induced hydrostatic infusion dispenses a drug from the familiar bottle suspended above the patient. Unfortunately, the IV set is not well-suited for use with an ambulatory patient.
Other methods for the gradual administration of drugs have been devised to eliminate the need for suspending the drug above the patient and thereby provide him with greater mobility. Mechanical pump dispensers use various types of mechanical pumps to expel the drug from a reservoir. Charged reservoir dispensers store a drug under pressure in a flexible reservoir and then selectively expel that drug by the force of internal reservoir pressure, the rate of release often being regulated by various valves. Pressurized gas dispensers use a pressurized gas to expel the drug. Osmotic dispensers rely on a solute that exhibits an osmotic pressure gradient against water to dispense the drug.
While the aforedescribed fluid administration techniques have served their purpose, there remains a continuing desire for further improvements therein.
When small quantities of drugs, such as hormones, are to be administered continuouly over a period of many hours, it is desirable to have a drug dispenser that is highly accurate and reliable, is sufficiently small and lightweight to be portable, and is convenient and easy to use. A copending patent application filed by Henri J. R. Maget, one of the instant inventors, entitled ELECTROCHEMICALLY DRIVEN DRUG DISPENSER, Ser. No. 729,860, filed May 2, 1985 now abandoned, discloses a drug delivery device which satisfies those needs. An electrochemical pump operating as a pressure source controls the delivery rate of small quantities of drugs. The pump is regulated by an external voltage supply and current controller.
The electrochemically driven drug dispenser disclosed in the above-mentioned patent application has many advantages, but additional improvements in the size, weight, cost, simplicity, flexibility and adaptability of drug dispensers are always desirable. A further need exists for a self-powered device which is compact, economical, simple in structure, and easy to operate, and which can be adapted to various applications requiring the gradual administration of drugs over an extended period of time. The present invention fulfills all of those needs.